i) Field of the Invention
This invention relates to a device which generates heat and to a method of generating heat.
ii) Description of Prior Art
Electrical heaters and other devices in which heat is developed electrically for different purposes all employ flow of electric current through an electrically conductive heating element. The heat generated by the heating element depends on the current flow and the electric resistance of the heating element.
The amount of heat produced is based on Joule's Law as set out in equation (I) EQU H.sub.c =I.sup.2 R (I)
where:
H.sub.c =heat in watts
I=current in amps
R=resistance in ohms.
This relationship may be expressed in more practical terms by equation (2) EQU H.sub.s =0.24I.sup.2 Rt (2)
In equation (2) the constant 0.24 is the heat equivalent of electricity, and
H.sub.s =watt seconds
t=time in seconds.
In existing heat generating devices the heat produced is controlled or varied by selecting or varying the current applied to the heating element, the resistance of the heating element being maintained constant.
Prior heat generating devices thus require increased amounts of electricity to raise the level of heat generation whereby operating the device at higher heat generation consumes a greater amount of electricity and thus higher cost.